The present invention relates to a printing wire and, more particularly, to a printing wire used for a wire dot printer.
Various systems have been proposed for printers as output devices for office equipment such as word-processors. Among these printers, a wire dot printer has been in widespread use since a special head is not required.
A conventional wire dot printer is shown in FIG. 1. Referring to FIG. 1, reference numeral 1 denotes a head case having leaf springs 3 fixed by bolts 2. The case 1 comprises a cylindrical member integral with a ring-like plate. A plurality of armatures 4 are arranged in the head case 1. Only two armatures 4 are shown in FIG. 1. One end of each of the armatures 4 is fixed by a corresponding leaf spring 3, and the other end of the armature 4 constitutes a free end. The free end of the armature 4 is fixed with a printing wire 6 having a striking portion at its distal end. The printing wire 6 is fitted in a guide hole 8 of a guide plate 7 and is guided. The guide plate 7 is fixed by a bolt on the head case 1. Electromagnets 9 are disposed in the head case 1 immediately under the corresponding armatures 4.
In this wire dot printer, an electromagnet 9 is turned on/off to vertically move the corresponding armature 4. Upon vertical movement of the armature 4, a corresponding striking portion 5 of the printing wire 6 extends outside from the head case 1 and transfers a color medium such as ink from an ink ribbon to a recording sheet on a platen (not shown). More particularly, when the electromagnet 9 is selectively turned on, the corresponding armature 4 is attracted to the electromagnet 9, and the printing wire 6 strikes a printing medium. However, when the electromagnet 9 is turned off, the corresponding armature 4 returns to an initial position by means of the corresponding leaf spring 3. In the conventional wire dot printer having the construction described above, the printing wire slides along the ink ribbon at a time of printing, and the printing wire must have high wear resistance.
A conventional printing wire comprises a tungsten carbide wire. Such a printing wire has high wear resistance, but is brittle when bent. The printing wire is easily damaged by careless handling, by rough surfaces on the recording sheet or the printing medium, resulting in inconvenience.
A titanium carbide wire has been developed to decrease the weight of a printer. However, the titanium carbide printing wire is also brittle when bent. In addition, the wire can be easily damaged by careless handling and by rough surfaces on the recording sheet and the printing medium. For these reasons, light-weight titanium carbide wire cannot be sufficiently utilized.